| Description |
Pan-concentrate sampling targeted, in order of decreasing preference: gravel/cobble-armored riffles, log/boulder/plunge-pool eddies, gravel/cobble-armored point bars, point bars, overbank flood deposits, and moss mats. Samples were collected with a shovel and screened using a Garretts Combination Sifter with a 0.483-inch, square-hole mesh. The resulting undersized material was collected in a 14-inch-diameter Garrett's Gold Trap gold pan. Sediments were screened until the gold pan was level full with -0.483-inch material. Using alternating shaking and washing motions, the sediment was reduced to visible heavy minerals or a volume of approximately 30 ml. This concentrate was then washed into Nasco Whirl-Pak plastic sample bags and placed in a cloth bag. Pan-concentrate samples were dried at DGGS using a drying oven and disposable paper trays, split using a Sepor splitter, and then pulverized to better than 85 percent passing 75 microns by ALS Minerals (PREP-31 package). Major- and trace-element compositions for stream-sediment, pan-concentrate, and rock samples were determined by ALS Minerals method ME-ICP61: Four-acid digestion followed by inductively coupled plasma-atomic emission spectrometry (ICP-AES) and inductively coupled plasma-mass spectroscopy (ICP-MS). Platinum, palladium, and gold values were analyzed by 30 g fire assay with ICP-MS finish (ALS Minerals method PGM-MS23) |